WATERLOGGING MODIFIES GROWTH, WATER-USE AND ION CONCENTRATIONS IN SEEDLINGS OF SALT-TREATED EUCALYPTUS-CAMALDULENSIS, EUCALYPTUS-TERETICORNIS, EUCALYPTUS-ROBUSTA AND EUCALYPTUS-GLOBULUS

Two experiments were carried out in a glasshouse in Canberra during autumn 1987 to determine the extent to which waterlogging would modify the response to salinity of E. camaldulensis Dehnh., E. tereticornis Smith, E. robusta Smith and E. globulus Labill. Seedlings, 4-5 months old, established in free-draining sand-filled pots, were treated with either 150 (experiment 1) or 100 (experiment 2) mol m-3 NaCl with and without waterlogging for approximately 4 weeks; a waterlogging pretreatment of 3 weeks was included in experiment 2. Salt x waterlogging (SW) significantly reduced seedling growth for all species whereas growth under NaCl (S) or waterlogging (W) treatment alone was not significantly affected, except for E. robusta. In addition SW significantly reduced leaf stomatal conductance and whole-plant water use and increased leaf and stem Na+ and Cl- concentrations. Pretreatment with waterlogging (experiment 2) significantly improved growth (particularly for E. globulus) and reduced the concentrations of Na+ and Cl- in leaves under SW treatment. E. camaldulensis showed least growth reduction and symptom development with addition of S, W and SW in these experiments.